CC0 Public Domain Dedication

CC0 is a Creative Commons legal instrument that allows a rights holder to place a work as close to the public domain as their jurisdiction permits. Development began in 2007 and the tool was released on March 11, 2009, with the scientific data community as a primary intended audience. Unlike the six core Creative Commons Licensing licenses, CC0 is structured as a waiver rather than a license. The rights holder first attempts a complete waiver of copyright and related rights (including database rights and certain neighbouring rights). Because some jurisdictions do not permit such waivers, particularly civil-law countries with unwaivable moral rights, the tool then falls back to a maximally permissive license granting essentially unlimited use without attribution. Patent rights and trademark rights are explicitly not waived. The key practical difference from CC BY is that CC0 imposes no attribution requirement, eliminating the compliance overhead that even the most permissive Creative Commons license carries. This matters most for data: a single dataset may combine thousands of contributions, and tracking attribution chains across downstream uses is infeasible. CC0 was endorsed by the Open Knowledge Foundation in 2014 as conformant with the Open Definition. Adoption highlights include large scientific repositories (genomic, astronomical, and chemical datasets routinely use CC0), the Metropolitan Museum of Art's open access collection, and the photo-sharing site Unsplash, which released several million photos under CC0 between 2013 and 2017 before switching to a custom license that disallowed bulk redistribution. CC0 is also frequently used for code snippets, fonts, and 3D-printable models where attribution would be impractical or unenforceable.